A mass spectrometer with multiple, independent stages of mass analysis can be used to increase throughput, speed of analysis and mass range in providing high resolution mass spectra, without imposing otherwise unavoidable and unrealistic requirements on a single analyser. This requirement is true for many different types of ion sources, including atmospheric pressure ion sources like APCI, API, ESI, MALDI as well as vacuum ion sources like EI, CI, v-MALDI, laser-desorption, SIMS and many others. Parallel analysis is especially effective for cases when analysis has low duty cycle, i.e. ratio of analyser fill time to analysis time is much less than 1. Advantageously, multiple stages may be used to analyse ions generated by a single ion source, in order that as little of the sample material be wasted as possible.
Sequential operation of mass analysers may increase specificity or mass range of analysis, but the throughput is limited by the capacity of the first mass analyser in the sequence. In contrast, parallel operation of mass analysers increases throughput and speed of analysis.
US-A-2002068366 relates to use of an array of parallel mass spectrometers to increase sample throughput for proteomic analysis. To allow flexibility, the mass spectrometers do not share components and the mass spectrometers each receive ions from an individual source. Hence, the mass spectrometers may be of different types.
Sharing analytical components between the stages of mass analysis may provide efficiency gains and cost reductions, although at the expense of this adaptability. An example of this loss of flexibility is U.S. Pat. No. 6,762,406, which describes an array of RF ion traps in parallel with a single ion source. The ion source is used either to fill one or more traps from an individual ion source or to fill multiple traps at once. This arrangement allows the source and traps to be housed in the same vacuum environment but it does not address the problem of low duty cycle because traps operate in parallel.
Parallel operation of different mass analysers connected sequentially can improve throughput, as shown in WO2005031290, but performance is still limited by the slowest detector in the chain.
Hence, existing methods and apparatus are unable to provide mass spectra from a single ion source using parallel mass analysers in an efficient way.